Nerve injuries, for example, injuries to peripheral, brain, or spinal cord nerves present considerable challenges to repair due to their physiological and morphological complexity. For example, spinal cord injury (SCI) is as any kind of trauma to the spinal cord that results in a loss of function such as movement or sensation. In the United States, there are approximately 250,000 people living with SCI, and 11,000 new injuries are reported every year.(14) Typically, with SCI the neuronal axons are compressed or transected, resulting in tissue damage, cell death, and loss of function.(15) Spinal cord injuries are particularly difficult to treat because the differentiated nerves of the central nervous system demonstrate a diminished capacity for regeneration.
Replacing the damaged tissue with nerves taken from other anatomic sites or allograft material is one option, but the best hope for complete or nearly complete recovery is to coax the damaged nerves to regrow. Schwann cell-laden grafts and nerve conduits have shown promise for repairing nervous tissue(16;17) and optic nerves(18), as have injections of olfactory ensheathing cells(19) and adult stem cells(20), but the size and complexity of the spinal cord warrants the development of specialized constructs.
Local electric fields have been measured during neural development or after nerve injury in various vertebrate systems. In addition, electric fields generated via electrodes can influence neural growth and orientation in vitro (Patel N B. J Neurosci. 1984; 4:2939-47) and have been applied for the treatment of spinal cord injuries in recent clinical trials (Duffell L D. Mus Nerve. 2008; 38: 1304-11).
Therefore, there is an ongoing need for therapeutic approaches with potential to treat and/or ameliorate the effects of nerve injury. Accordingly, compositions and methods that are capable of manipulating local electric fields and promoting cell and tissue growth and/or repair, for example, neuronal cell and tissue growth and/or repair, as presently described, present an opportunity for therapeutic intervention.